This invention relates to a new and improved geologic mapping and surveying apparatus for providing accurate, dependable and portable measurement of attitudes of planar surfaces in situations where magnetic compasses will not work.
The conventional, portable magnetic compass has several shortcomings inherent in its principle of operation. Every such instrument senses the earth's magnetic field lines by means of a magnetic element that orients itself to such lines. However, in certain environments, as for example, underground, where steel structures and magnetic rock may be found, a magnetic compass will not work. The standard of accuracy for magnetic compasses is the Bruton magnetic compass. However, a magnetic compass requires an environment where the earth's magnetic field is not severely interdicted by local influences.
Prior art devices such as described in U.S. Pat. Nos. 3,373,499, to Rothe et al and 4,033,045 to Wing et al, although utilizing gyroscopes for determining direction, utilize pendulous floated gyroscopes. The patent to Wing et al specifically excludes the use of gyroscopic instruments presently used on aircraft. Furthermore, the devices disclosed by the prior art require a long settling time before being capable of use. Other previously known methods of obtaining bearings where magnetic compasses are not appropriate consist of physically comparing the unknown directions to known directions by geometric relationships. This method is slow, tedious and therefore an expensive procedure.
The present invention provides a unique arrangement of the gyrocompass and power supply in a portable carrying case. A gyroscope is not dependent on the earth's magnetic field for a reference as is a magnetic compass. The present invention of a geological gyrocompass therefore is immune to disturbances in the earth's magnetic field and nearly duplicates the Brunton compass accuracy but does not require an environment free of magnetic anomalies.